Better then any gaming "headset" on that budget go with professional audiophiles headphone rather then headset as they lacks the audio quality to fit in the mic. If you would stretvh the budget you could get the Sennheiser HD 598 or the AKG Q701 which are very great for gaming. If you want to monitor go with the 598/Q701 as the AD700 have a very weak to no bass.
As for the mic, the Modmic is an attachable boom microphone that you could mount on your headphones so it acts like a gaming headset but with a better audio quality and a better mic. If you would like to get the Modmic i recommend waiting for the 4.0 version which should be releasing in Q1.